He was the son of King Oswald of Northumbria, who was killed at the Battle of Maserfield in 642.
However, when the armies of Oswiu and Penda met on 15 November at the Battle of the Winwaed, Œthelwald withdrew his forces.
Penda was defeated and killed,[2] perhaps in part because of this desertion, and afterward Œthelwald seems to have lost Deira to Alchfrith, who was installed there by the victorious Oswiu.
[3] Local tradition, however, held that he became a hermit in Kirkdale, North Yorkshire.
Although he allied himself with the pagan Penda, Œthelwald was a pious Christian and was remembered for his generosity towards St. Cedd, to whom he granted land for a monastery.